The overall objective of the total project is to gain an understanding of the metabolism of two anaerobic protozoan parasites, Giardia lamblia and Entamoeba histolytica. Special emphasis will be placed on comparative aspects of anaerobic metabolism as to their characterization and subcellular localization. In addition, an in-depth study of the enzymes responsible for production of end products will be conducted. Results obtained should increase our understanding of the evolutionary relationships among anaerobic parasitic protozoa. In addition, some insight should be obtained into the mode of pathogenicity of aerotolerant anaerobic parasites, and the mechanism of action of antianaerobic drugs used in the treatment of amebiasis and giardiasis.